Whenever the permit-issuing authority finds from the evidence adduced at hearing that a permit holder has willfully operated or caused to be operated a vehicle or vehicles in violation of this chapter, the permit-issuing authority may enter an order suspending, modifying, or revoking the permit in whole or in part at its discretion for a period not to exceed one hundred eighty days. If the permit-issuing authority finds in a subsequent proceeding within twelve months from the date of the initial suspension, modification, or revocation that a permit holder has again willfully operated in violation of this chapter, the permit-issuing authority shall order suspension, modification, or revocation of permit privileges in whole or in part for a period not to exceed two years.